Mercury pressure-gage



l (No Model.) 2'sneets-sneen 1. E. H. ASHCROFT.

MERCURY PRESSURE GAGE.

PatentedApr. 26", 1882.

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wg/2f (No Model.) 2 Sheets-Sheet 2.V

B.VH.ASHCR0FT. MERCURY PRESSURE GAGE.

Patented Apr. 25, 1882. I'

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UNITED STATES PATENT QFFICE.

EDVARD H. ASHCROFT, OF LYNN, MASSACHUSETTS- MERCURY PRESSURE-GAGE.

SPECIFICATION forming part of Letters Patent No. 256,814, dated April 25, 1852. Application lled August 8, 1881. (No model.)

To all 'whom it may concern Beitknown that I, EDWARD H. Asncnon'r, of Lynn, in the county of Essex and State Ot' Massachusetts, a citizen ofthe United States, have invented a certain new and useful Improvement in Steam-Gages, of which the following is a i'nll, clear, and exact description, reference being had to the accompanying drawings, forming a partof this specilication in explaining its nature, in which- Figure lis a vertical section, illustrating my invention. Fig. 2 is also a vertical section, illustratinga modification hereinafter described. Fig. 3 is afront elevation of the devices shown in Fig. l. FigAis'a horizontal section on the line a' x of Fig.,3. i n

My invention relates, first, to the method of operating a Bourdon spring by means of mercury under steam-pressure; and, second, means whereby the clogging of the steam-passage connecting the boiler with the gage is made known, and whereby the matter or material stopping the passage may be removed.

It is a well-known fact thatthe passage or tube connecting the boiler with the gage-operai:- ing mechanism contained in the casing of the steam-gage is very liable to be clogged bythe lodging ot' sediment within by the rusting of the pipe or by the freezing of water condensed therein, and that when a Bourdon spring is used for the device for actuating the index the same trouble is likely to arise in its passages, and that these disturbances and interruption of the action ot' steam upon the spring or upon any other instrumentality submitted to its action are liable to result very seriously, as they will cause the gage to register a less number of poundsofsteam than theactu al pressure. Therefore it is very essential that the Bourdon spring 'or other device used for communicating motion to the registering mechanism be connected with' the boiler in such a manner that it can be ascertained at any moment whether the steam has free passage therein and free access to the said spring or other instrumentality, and if not, have said obstruction removed immediately, and also that it be constructed so that the danger of the freezing of the condensed steam is made as slight as possible.

In the drawings, A represents the passage or steamway in the tube connecting the steamgage with the boilers B is a Bourdon spring. Instead, however, of making the spring ot' a composition containing more or less copper, I prefer to make the same ofsteel. This tube, instead ot'connecting at the point b directly with the steam-passage A, as in the ordinary gage, opens into the vertical chamber or passage b in the tube b2, and this tube, together with thechamber or chambers ofthe Bourdon spring, is filled with mercury to or about to the poi-nt b3. The steampassage extends from the point a, where it connects with the direct passage A, vertically to the point ct, where it enters the chamber a2, which connects it with the tube containing the mercury-column. This passage a may be within the tube a3, which is itself within the tube b2, the mercury-lube b inclosing it. Of course the mercury by this construction is under direct steam-pressure from the boiler, and it otl course imparts that pressure to the Bourdon spring in substantially the same manner that the direct steam-pressure within would impart pressure; and the Bourdon spring itself is provided with the same, or substantially the same, movement that would bevgiven it it' the steam or condensed steam directly entered its passage or passages, instead of exerting its force thereon through the medium of mercury,whi1e at the same time the arm or arms ofthe spring have a steadier, more regular, and uniform movement, owing to the steadying effect obtained by the method of communicating the steam-pressure and by the weight of the mercury than when steam alone is used. Besides these advantages the use of mercury eftectually precludes any danger from freezing. Steel or iron is used for the spring because they are substantially the only metals that can resist the action of mercury.

Itis unnecessary to herein describe the mechanism employed for converting the motion of' the end or ends of the Bourdon spring into a movement ot' an index-hand or other device for indicating the pressure of steam in pounds or units, and reference is made to various patents already granted to Bourdon, Lane, and myself for further information concerning the construction and operation of such mechanism. In order, however, that the mercury andsteampassages or tubes may not interfere with the IOO operation of such mechanism, I have provided a chamber, C, in the back of the gage and vgage is clogged or interrupted.

curve the steam and mercury tubes, so that they enter the same, and are therefore removed from interference with the registering mechanism. The gage-case also has a flange, c, extended backward so that it shall come in line With the outer surface, c', of the chamber C. To as certain whether there is a clear passage ofthe steam to the Bourdon spring, the chamber a?, or lo the gage I provide the steam-passage with ablow otl` cock, D. This may be located, as represented in Fig. l, so that its passage d shall connect with the chamber a2, or when a mercury column is not used or the tube a3 shall be not inelosed, as described, the blow-off can be located where shown in Fig. 2 or at or near the end of said passage connecting with the said chamber. Of course the chamber t2 must be sufficiently' large to provide for suitable steam-pressure upon the mercury column.

It will readily be seen that by opening the blow-ott' cock it is at once obvious whether or not the passage connecting the boiler with the It is also obvious that it' it is opened Vonce or twice a day and the steam allowed to blow through the tube it becomes practically impossible for it to cloo.

I am atv-are that English Patent No. 986 of 1874 describes the use of mercury in a steamgage for transmitting steani-pressure to the device for actuating the registering mechanism; and I therefore do not broadly claim the same, but simply the manner of its use as herein described. v

Having thus fully described my invention, I claim and desire to secure by Letters Patent of the United States- 1. The combination, in a steam-gage, of a Bourdon spring, a steam-chamber, a2, a steam supply pipe or tube, d3, entering said chamber, and a passage, b2, connecting the chamber with the passage or passages in the Bourdon spring, lled with mercury, all substantially as and for the purposes described.

2. The combination of a Bourdon spring, the tube b2, connected with the passages orchambersin the Bourdon spring, and with the steamchamber a2, the tube a Within said tube b2, and the said chamber a2, all substantially as and for the purposes described.

3. In a steam-gage, the combination of the steam supply-pipe, a pipe or passage connecting it with the passages ot' a Bourdon spring and adapted to contain mercury or other pressuretransmitting medium, and upon which the l steam is brought in direct contact, and a pas sage communicating with the outer air extending from the end of the steam-passage, having a suitable cock or valve for opening and closing the same, all substantially as and for the purposes described.

EDWARD H. ASHCROFT.

Witnesses:

F. F. RAYMOND, 2d, W. O. Foes. 

